288 BACTERIA AND DISEASE 



weakness, syncope, albuminuria, post-diphtheritic paralyses, con- 

 vulsions, and many other symptoms guide the physician in 

 diagnosis and the course of the disease. It begins as a local 

 disease, and the greyish-white membranous deposit, already referred 

 to, is produced. The toxins or poisons resulting from the growth 

 and multiplication of the bacillus are absorbed into the blood stream, 

 and general symptoms follow. The incubation period is from two 

 to seven days. 



Although diphtheria owes its name to the false membrane seen 

 in the throats of typical cases, it is now almost universally recognised 

 that in many cases of undoubted diphtheria no membrane is formed. 

 The occurrence of a nasal form of diphtheria has, too, in recent years 

 been recognised, and as such cases are not easily recognisable without 

 a bacteriological examination, they are very liable to remain undi- 

 agnosed and be left free to spread the infection. 



Thefons et origo of the disease is the specific bacillus. Without 

 the presence of that organism it is not possible to have diphtheria. 

 Yet that organism may exist in the healthy throat without producing 

 the recognised clinical symptoms of diphtheria. It may be conveyed 

 to the human throat in a variety of ways, for example, by kissing 

 and other forms of contact, or by drinking milk and other con- 

 taminated foods. In a perfectly healthy throat it may do no mischief. 

 But in a sore throat or in the throat of a weakly person, it might 

 readily set up severe and even fatal disease. Anything, therefore, 

 which tends to lower the vitality of the individual may play an 

 important part in propagating diphtheria, and must be as carefully 

 considered as any agency which might directly or indirectly introduce 

 the bacillus to the human throat. Some epidemics have been due 

 to school influence; other epidemics have been brought about 

 through an infected milk supply ; and yet other outbreaks are due to 

 the introduction of a case of diphtheria into a susceptible community, 

 weakened by insanitary surroundings or the prevalence of previous 

 sore throat. 



Further, there is reason to suppose that Bacillus diphtherias may 

 retain its virulence and possibly spend a stage of its cycle of 

 existence as a saprophyte in the soil, in dust, and even in the 

 throat for months. Three or four weeks is the average length of 

 time for its presence in the throat, but, as a matter of fact, all the 

 conditions in the" throat mucous membrane, blood-heat, moisture, and 

 air are extremely favourable to the bacillus, and it may linger 

 there far beyond the time of disappearance of clinical symptoms of 

 the disease. 



The Bacillus diphtherias was isolated from the many bacteria 

 found in the membrane by Loffler (1884). Klebs had previously 

 identified the bacillus as the cause of the disease (1883). It is a 



